3Sum is a rite of passage. Amazon, Meta, Google, Microsoft, Apple, Adobe, Bloomberg, Uber, and Oracle have all asked it. It's consistently in the top most-asked interview problems. Why? It builds directly on Two Sum but adds complexity: you need sorting, two pointers, and duplicate handling. It tests whether you can extend a known pattern to a harder problem. Common follow-ups: "What about 4Sum?" (add another loop), "What if we want the closest sum?" (3Sum Closest), "What about combinations that multiply to a target?"
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$ curl repovive.com/roadmaps/maang-interview-prep/two-pointers-sliding-window/3sum-why-this-problem
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